Biological method for preventing rancidity, spoilage and instability of hydrocarbon and water emulsions and also increase the lubricity of the same

ABSTRACT

A method for preventing degradation of physical and chemical properties, and for increasing lubricity, of a hydrocarbon and water emulsion, comprising adding to the emulsion an effective amount of at least one copper salt of a carboxylic acid for enabling at least one bacterium species from  Pseudomonas  genus to become dominant in the emulsion.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to the foreign patent application no.13915014000309916, filed in Iran on Feb. 24, 2013, which is herebyincorporated by reference, to the extent that it is not conflicting withthe present application.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable

REFERENCE TO SEQUENCE LISTING, A TABLE, OR A COMPUTER PROGRAM LISTINGCOMPACT DISC APPENDIX

Not Applicable

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates generally to hydrocarbon and water emulsions andmore particularly to a biological method for preventing rancidity,spoilage and instability of hydrocarbon and water emulsions and forincreasing the lubricity of the same.

2. Description of the Related Art

Oil and water emulsions are used in many industries such as metalmachining, textile, grease, metal forming, leather manufacturing, forvarious purposes such as cooling, lubricating, softening, corrosionprotection, etc. The oil and water emulsions are an ideal place formicrobial growth, which, if not prevented or controlled, causes thedegradation of the emulsions, including making the emulsions useless.

In some industrial systems, such as the machines used in cutting metals,when the system shuts down and the emulsion circulation stops, theoxygen level in the emulsion declines and the resulting anaerobicenvironment promotes anaerobic bacterial growth and increase in H₂S(hydrogen sulphide) gas which in turn causes an odor and reduction inthe pH, and an eventual emulsion breakdown and separation of oil andwater.

It is notable that the presence of fungi, yeast or mold, in theemulsions will result in a musty odor. Also, while, fungi usually do notaffect the performance of the emulsions, in some cases a heavy fungalgrowth could result in blockage of parts, such as in fluid transferpipes. In addition, the presence of fungi may have some harmful healtheffects on workers.

There has been considerable effort to improve emulsion formulations bymaking them bioresistant and by reducing the materials included in theformulations, which could be used as a food source by microbes. Some ofthe effort led to the use of a polymer with antimicrobial, biorestantproperties for metal working fluid and coatings. The bioresistant moietythat was linked into the backbone of the polymer is bromine/nitro group.In spite of all the effort and the solution provided (i.e., bioresistantpolymer), there is still much microbial growth noticed in such fluids.

Furthermore, in many emulsions, there are ingredients such ashydrocarbons, surfactants, sulfur and phosphorous, which are suitablenutrients for microbial growth, and are thus biosupportive and notbioresistant ingredients. In some emulsions, the microbial growth couldbe so intense as to affect the physical and chemical properties of theemulsion, such as pH, rheological performance, emulsion stability,corrosion protection and odor, and even emulsion breakage resulting inthe fluid becoming useless.

The level of destruction caused by the microorganisms depends on suchfactors as their type, population, the physical state of the system suchas temperature, cleanliness, type of water used, and the age of theemulsion.

Other efforts led to the proposal of methods for preventing microbialcontamination and degradation of emulsions, or other fluids containingbiosupportive ingredients, by using biocides. For this purpose, a rangeof various chemical compounds are produced and used. Some of thesebiocides are compounds containing chemical entities such as halogens,organometallics, quaternary ammonium, phenols, metal salts, polycyclicamines, formaldehyde, and sulfur. Biocide performance is calculated indifferent manners, which include considering their effectiveconcentration range (the optimum concentration for controlling themicrobial growth) and their power of microorganism destruction whichwill determine the effectiveness of the remaining biocide in theenvironment. Other considerations are biocide's stability, physicalproperties, toxicity level, economics and environmental aspects.

Many biocides used in the industry at the present are eitherbactericide, fungicide or both and they can eliminate most and sometimesall of the microorganisms present in the targeted environment. Thesebiocides could be part of the original formulation or could be added tothe system continuously or periodically as needed.

A drawback of using biocide as a method for controlling microorganismgrowth in emulsions is the fact that microbes are present in mostenvironments, such as air, water, soil and operators' hands and theycontinually contaminate the systems where the emulsions are used, andthus, the emulsions themselves. This causes the reduction and/or theelimination of the biocides in the respective emulsions, which, thus,require continual and/or periodical additions of biocides. Otherdrawbacks of biocides use are their adverse effects on the environmentand workers' health. Another drawback is that microbes become resistantto the used biocide and thus the biocide has to be changed periodically.

It should also be noted that not all the microorganisms and inparticular not all the bacteria in the nature are harmful towardsemulsions and some of them would not change the chemical and thephysical properties of such fluids. Contrarily, some of these bacteriapromote the stability of the emulsion by secreting biosurfactant whichhelps in stabilizing the emulsion and some might have biocidalproperties. Thus, killing all microorganisms by using biocides may becounterproductive.

Thus, as there is always a high potential for the hydrocarbon and wateremulsions to be attacked by microorganisms, to make them spoiled anduseless, there is a great need for a new and improved method that iseffective and economical in protecting them from such attacks, and thataddresses and solves the problems with the prior art described above.

The problems and the associated solutions presented in this sectioncould be or could have been pursued, but they are not necessarilyapproaches that have been previously conceived or pursued. Therefore,unless otherwise indicated, it should not be assumed that any of theapproaches presented in this section qualify as prior art merely byvirtue of their presence in this section of the application.

BRIEF SUMMARY OF THE INVENTION

This Summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This Summary is not intended to identify key aspects oressential aspects of the claimed subject matter. Moreover, this Summaryis not intended for use as an aid in determining the scope of theclaimed subject matter.

In one exemplary embodiment, a method is provided for preventing thehydrocarbon and water emulsions from becoming odorous, rancid, spoiled,unstable, or useless and for increasing the lubricity of the same. Thisis accomplished by using a certain fungicide and by providing acondition where a certain harmless bacterium grows and dominates theemulsions. Improvement in formulation of water and hydrocarbon emulsionsby this method will reduce cost, improve performance of the emulsions,and prevent health related issues. More particularly, a non-exclusivelist of advantages and benefits of the invented method is includes:prevention of spoilage and odor in oil and water emulsions; no need forperiodical addition of biocide to the emulsion for duration of its use;no need for addition of harmful biocides to the emulsion; inhibition ofgrowth of harmful and pathogenic microorganisms; ease of maintenance ofthe emulsion; decrease of the probability of pipes and passways to plug;increase of emulsion stability; increase of lubricity of the emulsion;suppression of anaerobic bacteria growth; improving stability in the pHof the emulsion; and, improving antioxidant properties of the emulsion.

The above embodiment(s) and advantages, as well as other embodiments andadvantages, will become apparent from the ensuing description, andaccompanying drawings if any.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

What follows is a detailed description of the preferred embodiments ofthe invention in which the invention may be practiced. The specificpreferred embodiments of the invention, which will be described herein,are presented for exemplification purposes, and not for limitationpurposes. It should be understood that structural and/or logicalmodifications could be made by someone of ordinary skills in the artwithout departing from the scope of the invention. Therefore, the scopeof the invention is defined by the accompanying claims and theirequivalents.

Pseudomonas species have been used effectively for biocontrol inagriculture. These species function in two ways in order to dominate themedia: by secreting materials which have biocide properties; and bydefeating the other competing microbes and reaching dominance byattaining most of the food source.

Aerobic bacteria such as strains of Pseudomonas genus commonly grow inoil and water emulsions in the presence of oxygen. These bacteriaconsume some materials present in the emulsion as their food.

In one aspect of the invention it was determined that Pseudomonasspecies, such as Pseudomonas Pseudoalcaligenus, Pseudomonas Putida andPseudomonas Fluorescens, are more benign aerobic bacteria species, whichdo not harm the emulsions. Along with many other microorganisms (many ofwhich could be harmful), these benign bacteria can grow in hydrocarbonemulsions, but they rarely ever become dominant. Thus, after finding themore benign aerobic bacteria species which do not harm the emulsions(i.e., Pseudomonas species, such as Pseudomonas Pseudoalcaligenus,Pseudomonas Putida, Pseudomonas Fluorescens, etc.), the associatedchallenge was to provide an environment where such benign bacteriaspecies will flourish and dominate the emulsion.

Adding a fungicide to the emulsion could prevent the growth of fungi inthe emulsion. However, while there are many fungicides which are used indifferent industries and products, almost all of them have bactericidaleffects as well, which in this case would retard or stop the growth ofthe benign bacteria, the Pseudomonas species, such as Pseudomonaspseudoalcaligenus Pseudomonas Putida, Pseudomonas Fluorescens. Thus,efforts had to be made to identify a fungicide which will not negativelyaffect the growth of the mentioned benign Pseudomonas species. This wasimportant, as again, the goal was to create the environment where thebenign Pseudomonas species become dominant in the emulsion and thus canfulfill the biocontrol function in the emulsion. The efforts led to thediscovery that copper salt of carboxylic acids, a fungicide used inagriculture, create the environment where the benign Pseudomonas speciesgrow and become dominant in the emulsion, thus, preventing orsignificantly reducing the growth of other, harmful microbes. This isanother aspect of the invention.

Thus, what is disclosed herein is a method for preventing thehydrocarbon and water emulsions from becoming odorous, rancid, spoiled,unstable, or useless, and for increasing the lubricity of the same. Thisis accomplished by using a carefully identified fungicide that providesa condition where a certain harmless bacterium grows and dominates theemulsions.

The fungicide is a copper salt of carboxylic acids, such as coppernaphtenate, copper adipate or copper succinate, and preferably is acopper salt of fatty acids, such as copper caprylate, copper levirate,copper palmitate, copper stearate, copper oleate and copper cruciate.The fungicide may also be a mixture of copper salts of carboxylic acids.

The copper salts of carboxylic acids, in addition to having fungicidalproperties, they can improve oxidation, stability, lubricating and wearproperties of the emulsion. The fungicide could be made in anemulsifiable form and used as a tank-side additive. The amount offungicide (i.e., a copper salt of carboxylic acid or a mixture of coppersalts of carboxylic acids) that may be added to the emulsion in order toachieve the results disclosed herein may be between 0.1 (zero point one)percent to 10 (ten) percent by weight.

Also, in addition to inhibiting fungal growth, the identified fungicidewill also hinder the activity of anaerobic sulfur reducing bacteria,which are a main cause of spoilage and odor in oil and water emulsions.Laboratory observations appear to indicate that in the presence ofcopper salt of carboxylic acids, the activity of anaerobic bacteriadeclines. As known in the art, sulphate reducing bacteria use sulphatesinstead of oxygen for respiration and acquire their needed energy fromoxidation of organic materials or hydrogen molecules during sulphatereduction to hydrogen sulphide. The formed hydrogen sulphide duringrespiration of these bacteria causes malodour and corrosion in thesystems using the emulsion. Thus, using the identified fungicide helpsprevent these undesirable results.

There is also a strong indication that, unlike the biocides commonlyused in metal working fluids and other industrial emulsions, theidentified fungicide does not have harmful health effects on, forexample, the operators of machinery using such fluids and emulsions. Itmay be postulated that the NFPA (National Fire Protection Association)health rating of two copper salt of carboxylic acids (Copper Stearateand Copper Oleate) is about 2 to 3 times better than that of commonlyused biocides.

Furthermore, because it is used in combination with the benign bacteria,as disclosed herein, the selected fungicide does not need to be addedperiodically or continuously to the emulsion, which is the case of thecommonly used biocides. A one-time addition of the selected fungicide tothe emulsion may be sufficient to create the environment where theselected benign bacteria become dominant, thus preventing the growth ofother harmful microorganisms.

Again, the chosen dominant microorganism belongs to Pseudomonas genuswhich represents Gram-negative aerobic bacteria. In particular, it isone of the more harmless species, such as Pseudomonas Pseudoalcaligenes,Pseudomonas Putida and Pseudomonas Fluorescens. The chosen dominantspecies are capable of growing in harsh environmental conditions.

A beneficial characteristic of the selected bacterium is that it cansecret biosurfactants, which improve the emulsion stability. Startingwith the known ability of the Pseudomonas strains to secretbiosurfactants, the biosurfactant secretion by the harmless Pseudomonasspecies and their effect on the pH increase and stability of emulsionwas observed during the development of aspects of the invention, and wasconfirmed and tested as explained hereinafter.

A sample of emulsions of emulsifiable oil containing copper salt ofcarboxylic acids in water was made with an initial pH of 9.1 and RI(Refractive Index) reading of 5 showing an oil concentration of 5(measured by a hand held refractometer). Diluted nitric acid was addedto this sample to lower the pH to 7.40 and the sample was divided it intwo new samples, 1 and 2. These two samples were left resting for 2 daysand then they were sterilized to kill all the existing microorganisms. Acream like layer was noticed at the top of both samples which is sign ofinstability in the emulsions.

At this point, sample 1 was inoculated with PseudomonasPseudoalcaligenes, which resulted in microbial count of 10³ CFU/ml and aRI reading of 2.9 and pH of 7.4. Nothing was done to sample 2 which alsoshowed a pH of 7.4 and RI reading of 2.9. Both samples were left into ashaker incubator for 10 days and then the pH and the RI of both sampleswhere measured. The pH of the sample 1 was 8.76, its RI read was 4.8 andits microbial count was 10⁷ CFU/ml. Sample 2 had a pH of 7.45 and a RIreading of 2.9. The results of this test is postulated in the belowtable, clearly showing biosurfactant secretion by the microbes in thesample containing Pseudomonas species, resulting in a pH increase andoil reemulsifying back into the emulsion, and thus, an increasedstability of the emulsion.

TABLE 1 Initial Microbial Counts Final Microbial Initial Final InitialFinal Sample (CFU/ml) Counts (CFU/ml) pH pH RI RI 1 10³  10⁷  7.4 8.762.8-2.9 4.8 2 0 0 7.4 7.42 2.8-2.9 2.8-2.9

Another beneficial characteristic of the selected bacteria is that thebiofilm produced is not considerable. For example, prior art data showsthat Pseudomonas Pseudoalcaligenes produces a biofilm having an averagethickness of only 0.50 μm, a maximum thickness of 10.45 μm and a biomassof only 0.62 μm³/μm².

The low amount of biofilm improves inhibiting the growth of theundesired microorganisms, and also prevents the blockage of industrialsystems. Reduction in biofilm formation further improves the stabilityof emulsion pH and its stability in general.

The low biofilm mass is very important for achieving the stability ofthe emulsions. As known in the art, biofilm formation causes anaerobiczones and provides suitable conditions for anaerobic bacteria growth.Thus, controlling the biofilm level helps control the growth of theanaerobic bacteria, which may be harmful to the emulsion. In addition,the formed biofilms are suitable zones for fungi growth. Also, usually,fungi, especially molds, grow more easily on areas where biofilm hasbeen formed and use the bacteria biofilm as their food source. Thus, ifthe biofilm formation is minimized, the growth of fungi and otherpollutants can be hindered as well.

Since the growth of fungi and anaerobic bacteria results in pH decreaseand emulsion instability, biofilm reduction and consequent reduction offungi and anaerobic bacteria growth will improve the emulsion stabilityand the stability of its pH levels.

Furthermore, formation of microbial mass as biofilm may plug pipes andreduce fluid flow. Thus, biofilm reduction will also help prevent thesecostly occurrences.

Thus, the inventive aspects are twofold: first, using a specialfungicide which will create an environment where harmful microorganismsto the emulsion are reduced or eliminated and certain harmless anduseful aerobic bacterium will grow to dominate the emulsion; secondly,adding some of the above-mentioned harmless and useful aerobic bacteriumto the emulsifiable hydrocarbon concentrate to initiate and help thedomination of such species in the emulsion.

Again, in order to prevent the growth of fungi and provide the suitablecondition for growth of the dominant aerobic bacterium, a copper salt ofcarboxylic acid or a mixture of copper salts of carboxylic acids may beused. The copper salt of carboxylic acid(s) could be a specific moleculeof copper and carboxylic acid or it could be a mixture of copper saltsof various carboxylic acids, which could have a plant or animal source,such as castor oil, tall oil, lard oil or tallow oil. Using the selectedfungicide promotes the growth and dominance of the selected benignbacterium by making the environmental condition difficult for othermicroorganisms to grow in the emulsion. Adding a specified amount of thedesired bacterium as a preculture to emulsifiable oil concentrate helpsthe domination of this bacterium. The addition of the bacterium to theemulsifiable oil concentrate could be done as a preculture, in a dry(lyophilized) or liquid form.

It should be noted that the raw materials of the emulsifiableformulations can be further manipulated, so the desired bacterium wouldgrow more easily and rapidly. There are many different ways and manydifferent raw materials which could be used to emulsify organicmaterials in water. Depending on the desired properties of the emulsionfor a particular use and the type of additives needed, one can selectand manipulate the raw materials to get the desired properties, such aspH, hydrocarbon droplet size, emulsion stability and so on.

The amount of preculture added to base emulsifiable hydrocarbon dependson the level of bacteria counts in the preculture and could be between0.01 to 10 percent, by weight.

The procedure for preparation of preculture and for adaptation ofbacterium is fully described in microbiological and scientificreferences such as ASTM 2275-03.

It is noted that the beneficial results described herein regardinghydrocarbon and water emulsions may be also obtained by simply adding tothe emulsion one or more of the copper salts of carboxylic acidsdescribed herein, so that an environment is created in the emulsion inwhich one or more of the benign Pseudomonas species may naturally growand become dominant. Thus, the addition of Pseudomonas species to theemulsion may not always be necessary. It may just be optional, such asfor aiding or expediting the natural growth and eventual dominance ofthe Pseudomonas species.

It may be advantageous to set forth definitions of certain words andphrases used in this patent document. A bioresistant material is onewhich, while it does not kill microorganisms, is not readily chemicallydecomposed by microbial attack. Simply put, a bioresistant material doesnot provide a ready food source for microorganisms. A biocide killsmicroorganisms.

The terms “include” and “comprise,” as well as derivatives thereof, meaninclusion without limitation. The term “or” is inclusive, meaningand/or. The phrases “associated with” and “associated therewith,” aswell as derivatives thereof, may mean to include, be included within,interconnect with, contain, be contained within, connect to or with,couple to or with, be communicable with, cooperate with, interleave,juxtapose, be proximate to, be bound to or with, have, have a propertyof, or the like.

As used in this application, “plurality” means two or more. A “set” ofitems may include one or more of such items. Whether in the writtendescription or the claims, the terms “comprising,” “including,”“carrying,” “having,” “containing,” “involving,” and the like are to beunderstood to be open-ended, i.e., to mean including but not limited to.Only the transitional phrases “consisting of” and “consistingessentially of,” respectively, are closed or semi-closed transitionalphrases with respect to claims. Use of ordinal terms such as “first,”“second,” “third,” etc., in the claims to modify a claim element doesnot by itself connote any priority, precedence or order of one claimelement over another or the temporal order in which acts of a method areperformed. These terms are used merely as labels to distinguish oneclaim element having a certain name from another element having a samename (but for use of the ordinal term) to distinguish the claimelements. As used in this application, “and/or” means that the listeditems are alternatives, but the alternatives also include anycombination of the listed items.

Throughout this description, the embodiments and examples shown shouldbe considered as exemplars, rather than limitations on the apparatus andprocedures disclosed or claimed. Although many of the examples involvespecific combinations of method acts or system elements, it should beunderstood that those acts and those elements may be combined in otherways to accomplish the same objectives. With regard to flowcharts,additional and fewer steps may be taken, and the steps as shown may becombined or further refined to achieve the described methods. Acts,elements and features discussed only in connection with one embodimentare not intended to be excluded from a similar role in otherembodiments.

The foregoing disclosure of the exemplary embodiments of the presentinvention has been presented for purposes of illustration anddescription. It is not intended to be exhaustive or to limit theinvention to the precise forms disclosed. Many variations andmodifications of the embodiments described herein will be apparent toone of ordinary skill in the art in light of the above disclosure. Thescope of the invention is to be defined only by the claims appendedhereto, and by their equivalents.

Further, in describing representative embodiments of the presentinvention, the specification may have presented the method and/orprocess of the present invention as a particular sequence of steps.However, to the extent that the method or process does not rely on theparticular order of steps set forth herein, the method or process shouldnot be limited to the particular sequence of steps described. As one ofordinary skill in the art would appreciate, other sequences of steps maybe possible. Therefore, the particular order of the steps set forth inthe specification should not be construed as limitations on the claims.In addition, the claims directed to the method and/or process of thepresent invention should not be limited to the performance of theirsteps in the order written, and one skilled in the art can readilyappreciate that the sequences may be varied and still remain within thespirit and scope of the present invention.

Although specific embodiments have been illustrated and described hereinfor the purpose of disclosing the preferred embodiments, someone ofordinary skills in the art will easily detect alternate embodimentsand/or equivalent variations, which may be capable of achieving the sameresults, and which may be substituted for the specific embodimentsillustrated and described herein without departing from the scope of theinvention. Therefore, the scope of this application is intended to coveralternate embodiments and/or equivalent variations of the specificembodiments illustrated and/or described herein. Hence, the scope of theinvention is defined by the accompanying claims and their equivalents.Furthermore, each and every claim is incorporated as further disclosureinto the specification and the claims are embodiment(s) of theinvention.

What is claimed is:
 1. A method for preventing degradation of physicaland chemical properties, and for increasing lubricity, of a hydrocarbonand water emulsion, comprising adding to the emulsion an effectiveamount of at least one copper salt of a carboxylic acid for enabling atleast one bacterium species from Pseudomonas genus to become dominant inthe emulsion.
 2. The method of claim 1, wherein the effective amount isabout 0.1 to 10 percent, by weight.
 3. The method of claim 1, furthercomprising adding to the emulsion at least one bacterium species fromPseudomonas genus in order to aid the enabled at least one bacteriumspecies from Pseudomonas genus in becoming dominant in the emulsion. 4.The method of claim 1, wherein the at least one copper salt of acarboxylic acid is from a group consisting of copper naphtenate, copperadipate and copper succinate.
 5. The method of claim 1, wherein the atleast one copper salt of a carboxylic acid is a copper salt of a fattyacid, which is from a group consisting of copper caprylate, copperlevirate, copper palmitate, copper stearate, copper oleate and coppercruciate, and wherein the lubricity of the emulsion is increased byadding the copper salt of a fatty acid to the emulsion.
 6. The method ofclaim 1, wherein the enabled at least one bacterium species is from agroup consisting of Pseudomonas Pseudoalcaligenes, PseudomonasFluorescens and Pseudomonas Putida.
 7. The method of claim 3, whereinthe added at least one bacterium species is from a group consisting ofPseudomonas Pseudoalcaligenes, Pseudomonas Fluorescens and PseudomonasPutida.
 8. The method of claim 3, wherein the added at least onebacterium species is added to the emulsion as a preculture amounting toabout 0.01 to 10 percent, by weight.
 9. The method of claim 1, whereinthe at least one copper salt of a carboxylic acid is made emulsifiableand then added to in-use or ready-to-be-used emulsion, as an additive.10. A hydrocarbon and water emulsion comprising at least one copper saltof a carboxylic acid.
 11. The hydrocarbon and water emulsion of claim10, further comprising at least one bacterium species from Pseudomonasgenus, wherein the at least one bacterium species is dominant in theemulsion.
 12. The hydrocarbon and water emulsion of claim 10, whereinthe amount of the at least one copper salt of a carboxylic acidcomprised by the emulsion is about 0.1 to 10 percent, by weight.
 13. Thehydrocarbon and water emulsion of claim 10, wherein the at least onecopper salt of a carboxylic acid is from a group consisting of coppernaphtenate, copper adipate and copper succinate.
 14. The hydrocarbon andwater emulsion of claim 10, wherein the at least one copper salt of acarboxylic acid is a copper salt of fatty acid, which is from a groupconsisting of copper caprylate, copper levirate, copper palmitate,copper stearate, copper oleate and copper cruciate.
 15. The hydrocarbonand water emulsion of claim 10, wherein the at least one bacteriumspecies is from a group consisting of Pseudomonas Pseudoalcaligenes,Pseudomonas Fluorescens and Pseudomonas Putida.
 16. The hydrocarbon andwater emulsion of claim 11, wherein the at least one bacterium speciesis added to the emulsion as a preculture amounting to about 0.01 to 10percent, by weight.
 17. A method for decreasing the activity ofanaerobic sulfur reducing bacteria in a hydrocarbon and water emulsionby adding to the emulsion about 0.1 to 10 percent, by weight, of atleast one copper salt of a carboxylic acid.
 18. The method of claim 17,wherein the at least one copper salt of a carboxylic acid is from agroup consisting of copper naphtenate, copper adipate and coppersuccinate.
 19. The method of claim 17, wherein the at least one coppersalt of a carboxylic acid is a copper salt of a fatty acid, which isfrom a group consisting of copper caprylate, copper levirate, copperpalmitate, copper stearate, copper oleate and copper cruciate.